Mixing apparatus



Aug. 25, 1959 Filed Oct. 21, 1957 C. E. STEDMAN MIXING APPARATUS 5 Sheets-Sheet 1 INVENTOR. CRESSWELL E. STEDMAN Aug. 25, 1959 c. E. STEDMAN 2,901,228

7 MIXING APPARATUS Filed Oct. 21, 1957 5 Sheets-Sheet :5

INVENTOR. Cg ssswax. E. STEDMANI B V Aug. 25, 1959 c. E. STEDMAN 2,901,228

MIXING APPARATUS Filed Oct. 21, 1957 5 Sheets-Sheet 4 INVENTOR. gRssswsLL E. STEDMAN M w M T l-H 55- 5 Sheets-sheet 5 Filed Oct. 21, 1957 INVENTOR. CRESSWELL E. STEDMAN E i-L1 United States Patent MIXING APPARATUS Cresswell E. Stedman, Chicago, Ill., assignor to US.

Acoustics Corporation, Coral Gables, Fla, a corporation of Florida Application October 21, 1957, Serial No. 691,268 11 Claims. (Cl. 259107) This invention relates to mixing apparatus. More particularly, the invention relates to mixing apparatus which may be employed to mix relatively heavy and viscous materials including, for example, those utilized in forming certain building products such as acoustical tile, various concrete aggregates, and the like.

One of the principal difiiculties encountered in the manufacture of various articles, including acoustical tile, concrete aggregates of various kinds, and the like, is in the mixing of the relatively heavy and viscous materials from which these articles are fabricated. The materials being mixed tend to adhere to the blades of rotary mixers and to accumulate thereon. As a consequence, incomplete mixing is frequently encountered and the final mixture may be deficient in some components and may be substantially non-uniform in constituency. Under these circumstances, the final product may be defective in its structural or other properties. Moreover, excessive shut down time to provide for cleaning of the mixing apparatus may be required and, in some instances, it may be necessary to replace portions of the mixing apparatus at relatively short intervals due to wear resulting from the accumulation of materials thereon.

An object of the invention, therefore, is a new and improved mixing apparatus which effectively overcomes the foregoing and other difilculties encountered in the use of previously known mixing apparatus. Another object of the invention is a new and improved mixing apparatus which is especially designed, constructed and arranged for mixing relatively thick, heavy and viscous materials such as the aggregates utilized in the fabrication of various building products.

An additional object of the invention is a new and improved rotary mixing apparatus which includes means for preventing the material being mixed from adhering to and piling or balling upon the rotary mixing blades or members.

A more specific object of the invention is a new and improved rotary mixing apparatus embodying a novel construction and arrangement for wiping horizontal and vertical elements of the rotary mixing members as the members rotate within the mixer.

Other and further objects of the present invention ing two mixing apparatus units constructed in accord- ,ance with the invention and disposed in vertically staggered relationship with respect to each other;

2,901,228 Patented Aug. 25, 1959 Fig. 2 is a vertical sectional view of a mixing apparatus constructed in accordance with the invention;

Fig. 3 is a vertical sectional view taken along line 3-3 in Fig. 2;

Fig. 4 is a plan View of the mixing apparatus of Figs. 2 and 3;

Fig. 5 is a perspective view of one of the rotary mixing members of the mixing unit; and

Fig. 6 is a partly sectional isometric view illustrating the construction of the novel rotary mixing apparatus.

Fig. 1 illustrates a mixing machine 10 which embodies two mixing apparatus units 11 constructed in accordance with the present invention. The mixing apparatus units 11 are substantially identical in construction; accordingly, the structure and arrangement of only one of the units is described in detail hereinafter. In the particular machine 14} illustrated in Fig. l, the mixing units 11 are arranged in vertically staggered relationship and are connected by a delivery chute 12 through which the batch material may flow from the upper mixing apparatus to the lower mixing unit. The lower mixing unit, in turn, discharges into a conveyor 13 which conveys the mixed material to a fabricating station (not shown) to be molded or otherwise formed into structural units such as acoustical tile or the like.

Each of the mixing apparatus units 11 comprises a cylindrical mixer housing or tub 14, the top portion of which is open. A spider or support structure 16 is mounted within the upper part of the mixer housing 14; the spider 16 includes four arms 17, 18, 19 and 20 which are welded or otherwise suitably secured to a central ring 21. The ends of the arms 1720 rest upon the upper surface 15 of the mixer housing and are welded or otherwise affixed to an annular member 22 which is disposed in partially overlapping relationship with respect to the external surface of the mixer tub.

A clamping ring 23, which is of approximately. the same dimensions and configuration as the mixer housing 14, is disposed above the support spider 16 and engages the outer ends of the arms 17-20. A plurality of clamps 24 are affixed to the ring 23; these clamps are utilized to secure the clamping ring to the mixer unit. The clamps 24 may, for example, comprise conventional wing nuts which engage in suitable threaded openings in the support members 25 which are utilized to support the mixer unit 11. Thus, the clamps 24 maintain the ring 23 in the desired position at the top of the mixing unit 11 and the clamping ring, in turn, effectively maintains the annular member 22 and the spider 16 in fixed position with respect to the mixer housing 14. Preferably, the annular member 22 extends into overlapping engagement with respect to the upper ring 23 as well as the housing 14.

The mixing unit 11 further includes a rotary mixing mechanism comprising a shaft 3% which extends upwardly into the mixer housing 14 through a suitable aperture preferably located at the center of the base 31 of the housing. A bearing housing 32 is mounted in fixed position on the base 31 of the mixer housing, being disposed in co-axial encompassing relation with respect to the drive shaft M). A hearing unit 33 may be mounted on the drive shaft 3th for rotation therewith and in engagement with the interior surface of the bearing member 32 to maintain the shaft 30 in vertical alignment within the housing 32. The shaft 30 may be driven by any suitable means directly coupled thereto, such as an electrical motor, or may be driven by a belt drive arrangement 35 as illus trated in Fig. l.

A substantially disc-shaped cap member 36 is mounted upon the upper end of the drive shaft 30 and is secured to the shaft for rotation therewith in any suitable manner,

as by welding. The cap member engages the upper surface of the bearing housing 32, affording a thrust bearing for the rotary drive mechanism of the mixer. The cap member 36 lso s ppo t a P f o a y x ng blademen bers or paddles 37 and 3 8. As best indicated Fig. 3;, the blade members 37 and38 are disposed in suitable recesses or apertures 39 and 40 in the upper l,lrfiflce of the cap. member 3.6 and are maintained in position by a second or upper cap member 42. The second gap member .42 may be secured to the first cap member 36 in any suitable manner which permits removal of the upper cap for replacement of the blades. In the illustrated embodiment, the upper cap i threaded onto the lower cap. If desired, studs or other suitable removable fast ning means m y be mpl ye The configuration of the blade members 37 and 38 may bestbe understood by reference to Fig. 5, Which is a Perspective view of the blade member 37. As indicated therein, the blade member 37 is shaped substantially like a squared-off letter J and includes an upper horizontally extending portion 44; it is this part of the blade which fits into the recess ,39 in the cap 36 of the rotary mechanism. The blade 37 further includes a vertically depending portion 45 which, as indicated in Fig. 2, engages the outer surface of the bearing housing 32 in wiping contact therewith. At the lower end of the blade portion 45, a horizontal section 46 extends outwardly, and in wiping contact with the base .31 .of the mixer housing 14, toward the internal surface of the outer wall of the mixer housing. A further vertical section 47 .of the blade extends npwardly from the end of horizontal blade section 46 and enga es the inner surface of the wall of the mixer housing in wiping contact therewith. The leading edges of the blade sections 45, 46, and 47 are all beveled, as filearly indicated in Fig. 5.

As thus far described, the rotary mixing apparatus unit 11, with the exception of the spider 16 and the clamping ring arrangement which maintains it in position, is substantially conventional in construction. When the mixing apparatus is to be placed in use, the materials to be mixed are introduced into the mixer housing 14, usually through the open top portion thereof. The drive means'connected to Shaft 30 is energized, rotating the shaft, the cap 36, 42, and the mixer blades ,37 and 38. In the illustrated apparatus, the rotational movement is in a clockwise direction as indicated in Figs. 2-4 and 6 by the arrows A. The rotational movement of the mixer blades 37 and 38 afiord the desired mixing action, the beveled edges of the blades tending to loosen and detach any material in the batch being mixed which may adhere to the surfaces of the mixer housing or the bearing housing 32. Where the materials being mixed are relatively thick and viscous, however, they may tend to adhere to and pile up on the surfaces of the blades themselves. 'When this occurs, mixing of the piled-up materials is no longer possible and, as a consequence, the desired intimate mixing of the different components of the batch is not realized. This difficulty may produce extremely undesirable results in many applications and, indeed, may render the mixing apparatus completely useless for its intended purpose.

, In the mixing apparatus unit 11, however, the piling up and consequent failure of mixing in the unit is eitectivel y eliminated by means of certain structures supported from the spider or support structure 16. Thus, the mixing apparatus unit 11 includes four vertically depending stationary mixer arms 57. 58, 59 and 60 which are affixed to and extend downwardly from the spider arms 17, 18, 19 and 20 respectively. The mixer arms 5760 may be mounted on the support arms 1720 by welding or by any other suitable means which rigidly secures the depending mixer arms in fixed position on the support .arms. As best indicated in Fig. 4, the four mixer arms .5760 are not located at equal radial distances with "respect to the central axis of the mixer. The mixer arm 4 57 is disposed in spaced relation to the inner surface of the housing 14 but is spaced by a substantially greater distance from the bearing housing mixer. The mixer arm 58 is located at a relatively small distance from the bearing housing 32. The mixer arm 59 is located only a very short distance from the inner wall of the mixer housing 14, being substantially closer to the wall than the mixer arm 57 at the opposite side of the mixing unit. The vertical arm 60, on the other hand, is located somewhat closer to the bearing housing than is arm 57 but is spaced therefrom by a greater distance than the mixer 58. Thus, the stationary mixer arms are disposed within the cylindrical mixer housing with substantially different angular and radial displacements with respect to the axis of the housing.

The leading edges 61, 62, 63 and 64 of the four vertical mixer arms 57, 58, 59 and 60 respectively are all beveled, thereby alfording a series of substantially V- shaped surfaces facing the batch material as it is rotated within the mixer housing. The trailing edges .67, 68, .6-9 and 7-0 of the vertical mixer arms, on the other hand, are each preferably provided with a series of tapped open.- ing which are distributed vertically along the mixer arms; this arrangement is best illustrated in Figs. 2, 3 and 6.

A first resilient wiper or scraper member 71 is secured to the trailing edge .67 of the vertical arm 57. The Wiper member 71 comprises a coil spring or other spring-like member mounted in a suitable holder 72 which is bolted or otherwise secured to the trailing edge of the vertical mixer arm 57. The wiper member extends inwardly of the mixer housing, at an angle, as indicated in Fig. .4, and is also oriented to extend downwardly into contact with the base 31 of the mixer housing 14. A second wiper or scraper member comprising a coil spring 73 is affixed to the trailing edge 68 of the vertical arm 58 as by a holder 74. The resilient wiper member 73 extends downwardly and inwardly from the trailing edge 68 of the vertical arm 58 and is so oriented that the .end of the coil spring is normally located at the junction of the bearing housing 32 and the base 31 of the mixer housing. The mixer apparatus further includes a third resilient wiper member 75 comprising a coil spring or other spring-like member secured to the trailing edge 69 of the mixer arm 59 by a suitable holder 76. The spring 75 extends downwardly from the vertical mixer arm 59 and, in its normal position, terminates approximately at the junction of the vertical wall of the housing 14 with its base 31, A fourth resilient wiper member 77 is m unted on the tra ing edge 70 of th rtical mixer a m 69 as y means f a s i a l holder 78; this r silien wip r em er ex end d nwa d y an u wa dly from the vertical mixer arm and terminates at the base of the mixer housing.

The mixing apparatus unit 11 also includes two additional resilient wiper or scraper members 80 and 81. The wiper member .80 comprises a flat substantially Iectangw lar or box-shaped spring member having two horizontally extending arms 82 and 83 joined by a vertical section The ends of the two arms 82 and 83 are secured to the trailing edge 67 of the vertical mixing arm 57 by suitable holders; preferably, the holders afford means for mounting the resilient wiper member with screws, studs or other removable fastening devices in order to permit removal of the wiper member for cleaning and other purposes. The vertical wiper member 80 extends outwardly from the trailing edge .67 of the mixer arm 57 at an angle with respect thereto and normally engages the inner surface of the vertical wall of the mixer housing 14.

The second vertical wiper member 81 is similar in .construction to the member 80 and includes horizontal arms 86 and 87 joined by a vertical section 88, the ends of the two horizontal arms being removably fastened to the .trailing edge .69 of the vertical mixer arm 59. The wiper 31 extends outwardly from the trailing edge 69 of the vertical frnixer arm at an angle with respect thereto to lg.) engage theinner surface of the vertical wall of the mixer housing 14. Thus, the mixer apparatus includes a plurality of different spring-like wiper members, including the members 71, 73, 75, 77, 80 and 81, each of which may comprise a spring or other suitable spring-like member resilient throughout its effective wiping length.

When the mixing apparatus unit 11 is placed in operation, as described hereinabove, the batch of materials to be mixed is introduced into the housing 14. If desired, the housing may be covered as by a cover or lid 90 (Fig. 1) and the drive shaft 30 is set in rotation, impelling the mixer blades 37 and 38 to rotary motion within the housing as indicated hereinbefore. As a consequence, the entire batch of materials tends to move to some extent in the direction of rotation of the blades, which in the illustrated embodiment is assumed to be clockwise as indicated by the arrows A.

As blades 37 and 38 rotate, however, they engage the resilient wiper elements 71, 73, 75, and 77. Considering wiper element 71 as an example, as one of the blades 37 or 38 engages the end of the wiper member, the wiper is forced upwardly over the surface of the central horizontal portion 46 (see Fig. 5) of the blade. Moreover, the end of the spring element is forced outwardly by engagement with the wiper blade and consequently scrapes across a substantial portion of the center section 46 of the blade. When the same blade nextencounters the resilient wiper element 73, the innermost part of the horizontal section 46 is scraped or wiped, including the corner portion of the blade. Continued rotation of the same blade brings it into engagement with the next resilient wiper element 75, which scrapes across the outermost portion of the horizontal blade section 46, and also scrapes the lowermost part of the vertical blade section 47. Thereafter, further rotation of the same blade brings it into engagement with the fourth resilient wiper member 77, which scrapes across and wipes an intermediate part of the horizontal blade sector 46. In this manner, the four resilient wiper members 71, 73, 75 and 77 engage different portions of each of the two blades 37 and 38 as the blades are rotated to wipe or scrape the blades andprevent accumulation of any substantial quantities of the material being mixed on the blades.

The mixing action of the mixer unit 11 is also materially improved by the vertical mixer arms 57-60. These mixer arms, which extend down into the material being mixed, tend to break up the flow of material within the mixer and create substantially greater turbulence than would be obtained in a conventional mixing device. The beveled forward edges of the stationary mixer arms permit a relatively clean flow of the material over and around the arms and prevent them from exerting undue drag on the mixer apparatus. At the same time, of course, the mixer arms afford a convenient and effective means for mounting the resilient wiper members within the mixer housing in positions in which they may effectively engage the rotary mixer blades 37 and 38.

The vertical wiper elements 80 and 81 also perform an important function in operation of the mixing apparatus unit 11. With at least some batch constituents, the materials being mixed may tend to accumulate and to pile up on the vertical outer portions 47 (Fig. 5) of the blade members. This is effectively prevented by the resilient wipers 80 and 81, which engage the mixer blades as the latter are rotated within the housing 14 and scrape across the vertical outer portions thereof. In this manner, accumulation is prevented on this portion of the rotary blades as well as on the horizontal sections thereof. Inasmuch as the rotary motion of the mixer tends to impel the materials being mixed outwardly of the housing 47 and away from the interior vertical portions 45 of the rotary blades, it is not usually necessary to afford any means for preventing accumulation of the batch materials on these elements. If necessary, however, these may also be wiped or scraped by suitable resilient mem- 6 bers corresponding to the vertical wiper elements and 81.

Disassembly of the major components of the mixing unit 11 for cleaning or repair is extremely simple. To remove the spider 16 and its associated members, it is only necessary to loosen the clamps 24 and remove the clamping ring 23, after which the entire spider, including the annular member 22, may be removed from the mixer housing. It is, therefore, a simple and convenient matter to remove or clean any or all of the resilient wiping members. To repair or clean the blades 37 and 38, it is only necessary to remove the upper cap member 42, making it possible to lift the rotary blades 37 and 38 from their recesses in their lower cap member 36. In this manner, the entire mixing unit can be quickly and efficiently cleaned or parts may be replaced as required.

The mixing apparatus of the invention effectively prevents accumulation of batch materials upon the rotary members of the mixing mechanism and substantially prolongs the periods during which the mixing units may be maintained in operation without requiring cleaning. By preventing accumulation of the materials on the rotary blades of the mixer, the wear of the mixer parts is substantially reduced, affording longer operating life for the mixer. The mixing apparatus is particularly effective when applied to the mixing of thick, heavy, and viscous materials such as the aggregates utilized in the fabrication of building products, including acoustical tile and the like. The construction is relatively simple and inexpensive, yet affords substantially improved results as compared with previously known apparatus.

While preferred embodiments of the invention have been described and illustrated, it is to be understood that these are capable of variation and modification. Accordingly, the aim in the appended claims is to cover all such variations and modifications as may fall within the true spirit and scope of the invention.

I claim:

1. A mixing apparatus comprising a mixer housing, at least one rotary blade member adapted to rotate within said mixer housing to mix batch materials disposed therein, support means mounted within said mixer housing, and wiping means comprising a plurality of wiper members mounted on said support means in the path of travel of said blade member for engaging said blade member to wipe batch material therefrom, each of said wipers being a spring-like member resilient throughout its effective wiping length. a

2. A mixing apparatus comprising a mixer housing, at least one rotary blade member adapted to rotate within said mixer housing to mix batch materials disposed therein, support means comprising a plurality of stationary mixer arms extending downwardly into said mixer housing, and wiping means comprising a plurality of elongated transversely resilient wiper members mounted on said stationary mixer arms in the path of travel of said blade member for engaging said blade member to wipe batch material therefrom.

3. A mixing apparatus comprising a cylindrical mixer housing having a stationary cylindrical bearing housing disposed at the center thereof, a drive shaft extending through said bearing housing, at least one rotary blade member connected to said drive shaft and adapted to rotate within said mixer housing to mix batch materials disposed therein, said blade member including a vertically depending section which engages the external surface of said bearing housing in wiping contact therewith, a horizontal section which engages the base of said mixer housing in wiping contact therewith, and a vertically upwardly extending portion which engages the inner wall of said housing in wiping contact therewith, support means mounted within said mixer housing above said blade member, and wiping means comprising a plurality of resilient cantilever wiper members mounted on said support means and extending downwardly therefrom into the path of travel of said blade member for engaging said horizontal sections of said blade member to wipe batch material therefrom.

.4. A mixing apparatus comprising an open-top -closed base substantially cylindrical mixer housing, at least one substantially -J:shaped notary blade member adapted to rotate within said mixer housing to mix batch materials disposed therein, support means mounted .on the upper portion of said mixer housing and comprising a plurality of stationary mixer arms extending downwardly into said mixer housing, and wiping means comprising a plurality of resilient wiper members mounted on the lower portions of said stationary mixer arms and extending downwardly therefrom at an acute angle to the base portion of said blade into the path of travel of said blade member for engaging the lower portion of said blade member to wipe batch material therefrom.

'5. A mixing apparatus comprising a mixer housing, at least one rotary blade member adapted to rotateabout a given axis within said mixer housing to mix batch ma.- terials disposed therein, support means mounted within said mixer housing, and wiping means comprising a plurality of wiper members mounted on said support means at varying radial and angular displacements with respect to said axis and extending into the path of travel of said blade member for engaging said blade member to wipe batch material therefrom, each of said wipers being a spring-like member resilient throughout its elfective wiping length. I

6. A mixing apparatus comprising a substantially cylindrical mixer housing, at least one rotary blade mem- 'ber adapted to rotate within said mixer housing to mix batch materials disposed therein, support means comprising a plurality of stationary mixer arms extending downwardly into said mixer housing, and wiping means comprising a plurality of coil springs mounted on the lower portions of said stationary mixer arms and extending downwardly and horizontally into the path :of travel of said blade member for engaging said blade member to wipe batch material therefrom.

7. A mixing apparatus comprising a substantially cy- 'lindrical mixer housing, at least one rotary blade member adapted to rotate about the axis of said mixer housing in wiping contact with the base and walls thereof to mix batch materials disposed therein, support means comprising a plurality of stationary mixer arms extending downwardly into said mixer housing at substantially vary ing radial and angular displacements With respect to said axis and wiping means comprising a plurality of .coil springs mounted on the lower portions of said stationary mixer arms and extending downwardly and horizontally therefrom into the path of travel of said blade member for engaging said blade member to wipe batch material therefrom.

8. A mixing apparatus comprising a substantially ,cy lindrical mixer housing, .at least one substantially J- shaped rotary blade member adapted to rotate within said mixer housing to mix batch materials disposed therein, support means comprising a plurality of stationary mixer arms extending downwardly into said mixer housing, and wiping means comprising a plurality ,of resilient cantilever wiper members mounted ion. the lower portions of said stationary mixer arms in the path of travel :of said blade member for engaging thehorizonz al portion of said blade member to wipe :batch material therefrom, .said wiping means further including at least one additional resilient wiper member mounted on one of said stationary mixer arms and extending outwardly therefrom to engage the outer vertical portion of said blade member to wipe batch material therefrom.

9. A mixing apparatus as set forth in claim ,8 whieh said plurality of wiper members comprise coil springs and in which said additional wiper member comprises a sub.- stantially rectangular wire spring.

1.0. A mixing apparatus as set forth in claim 3 in which said additional wiper element extends outwardly from its stationary mixer arm at an acute angle with respect to said rotary blade and normally engages the inner wall surface of said ho si g- 11. A mixing apparatus comprising a vertical cylindrical m xer hous n h ving tant a y pl n as a stationary cylindrical bearing housing disposed at the center of said housing 'base and extending upwardly into said housing, a drive shaft extend-ing through said heat- ;housing, a of rotary blade members connected to said drive shaft and adapted to rotate within said mixer housing t ba c a r s d p ei said blade members each including a vertically depending section which engages the external surface of said bearing housing in wiping contact therewith, a horizontal section whieh engages the base pf said mixer housing in wiping n a t t e ewi and a ve l y up y ex n in portion which engages the inner wall of said housing in wiping contact therewith, stationary support means mounted within said mixer housing above said blade m m r an i cl ng a p ura ty of i n ry mi er arms extending downwardly into said housing, and wiping means c mprising a corresponding plurality of elongated transversely resilient wiper members mounted on said support means and extending downwardly and horizontally therefrom into the path of travel of said blade members for engaging said horizontal sections .of said blade members to wipe batch material therefrom, said wiping means further including at least one additional resi-lient wil t l' member mounted on and extending outwardly therefrom to engage the vertically upwardly extending portions of said blade members to wipe batch material therefrom.

References Cited in the file of this patent UNITED STATES PATENTS 733,471 Ellis et al. July 14, 1903 966,080 Cameron Aug. 2, 1910 1,131,260 Nydegger Mar; 9, 1915 1,406,457 Hot'tmann Feb. 14, 1922 1,490,980 Minney Apr. 22, 1924 FOREIGN PATENTS 88,991 Germany Oct. 31, 1896 278,152 Great Britain Oct. 6 1927 

